Link injection into head section

Hello,
There is this link injected into my site’s head section, driving me crazy. It is appearing on the site too.

I have updated everything, WordPress, themes, plugins…checked all the php files i could, but to no avail how it is getting injected into my site.

A special trait here is that after I access wp-login.php of the site (not even logged-in), the link does not appear for any user using the same IP address.

Does anyone have idea how to resolve the issue.

Thanks in advance…